Six months after US-Israeli strikes against Iran, the war appears to be at a stalemate.
A preliminary ceasefire accord reached in June has unravelled and little progress has been made in diplomatic efforts to get the peace process back on track.
After a pause in military action for much of July, tit-for-tat strikes have resumed, with US Central Command saying it hit three Iranian tankers on Saturday in response to Iran's Islamic Revolutionary Guard Corps launching ballistic missiles at two US Navy ships.
Following the attacks, Iran's Parliament Speaker Mohammad Baqer Qalibaf said on Sunday the US should understand the rules of the game in the war against Iran had changed "before it is too late".
"From now on, any attack against Iran's interests and security will receive a faster, heavier and more painful response," he said in a speech published on his Telegram channel.
Tehran has shown it retains the capability to attack US interests in neighbouring countries and to shut down oil flows through the Strait of Hormuz, through which a fifth of global oil supplies previously flowed.
However, the US campaign to throttle Iran's economy by blockading its oil exports and stopping sanctions evasion is growing increasingly difficult to withstand, three senior Iranian sources have said.
In his speech on Sunday, Qalibaf added that alongside the military front, Iran's main battle was now over production and people's livelihoods.
He cited sharp currency fluctuations, inflation, unemployment and market management as major challenges, adding Iranians could tolerate hardship but not mismanagement or inaction and expected the government to act quickly.
Iran's Economy Minister Ali Madanizadeh said Tehran planned to respond to US economic pressure with reforms and rejected the idea sanctions would cause it to change course, according to state media.
"They speak of economic pressure and isolation, of breaking off financial ties and they think that by pressuring the economy of a country they can change the decisions of its people," Madanizadeh said.
"I have to clarify one point: the responsibility of reforming Iran's economy is with its government and people, not with the US Treasury."
Separately, Economy Ministry deputy Morteza Zamanian said on Sunday the ministry's "Economic War Headquarters" was doubling down on its work to resolve problems caused by the war, according to the semi-official Tasnim news agency.
Iran is the third-largest producer in the Organization of the Petroleum Exporting Countries and exported 90 per cent of its crude via its Kharg Island export hub before the war.
Flows have been disrupted since a US blockade of Iranian oil exports began in mid-April.
On August 31, Trump issued a one-line social media post accompanied by an AI-generated video depicting Kharg Island being "blown to smithereens".
Iranian authorities have vowed a strong response if Kharg is attacked.
In an interview aired on state TV on Sunday, Iran's Oil Minister Mohsen Paknejad said the island had been hit about 550 times in previous months but continued to operate.
Iran has also imposed a blockade on the Strait of Hormuz, creating an issue for US President Donald Trump by pushing up global fuel prices ahead of midterm elections for his Republican Party in November.
On Saturday, US Central Command said it struck three Iranian vessels, including one off the coast of Kharg Island, after Iran's Islamic Revolutionary Guard Corps launched ballistic missiles at two US Navy ships.
The IRGC responded by threatening intensified strikes against US military vessels in the region, and said later it targeted the three tankers as well as three US-linked vessels in other areas.
